Yep 100 %Only me or has he been pretty bad this season. He's seemingly declined although not as badly as Vertonghen.
His 1on1 defending has been very bad and a lot of mistakes have started creeping in + I don't think he's as switched on as he used to be . Also read a Stat that he has the worst ariel duels win % of any premier league player (not good).
Sanchez for me is 9/10 against the top teams but 5/10 against the lower half teams.
At the moment neither Alderweireld or Sanchez would be starting ideally.
Buying a CB this window really needs to be a priority.
For me Sanchez gets too tight to the attacker.
His decision making needs to improve, when to challenge for the ball or when to step off.
At times he looks good and at others he gets turned too easily.
He could be great if he can sort that out.